Most people wind up using the same handful of layer blend modes—Multiply, Screen, Overlay, Hard Light, and Soft Light. If those sound like your favorites, you can save yourself some time by jumping directly to the one you want using a simple keyboard shortcut. For example, to jump directly to Screen mode, you’d press Option-Shift-S (PC: Alt-Shift-S); for Multiply mode, you’d press Option-Shift-M (PC: Alt-Shift-M); and so on. To run through the different shortcuts, just try different letters on your keyboard.

From Scott’s The Adobe Photoshop CC Book for Digital Photographers.